Synthesis of graphene paper from pyrolyzed asphalt

A new technique for the synthesis of large sheets (>10 cm2) of multi-layered graphene is presented. The condensation onto a heated surface (≈650 °C) of fumes from the thermal decomposition of asphalt in a ceramic crucible produces carbon films with a metallic sheen. Heating was done by a Fisher burner (natural gas/air) flame and the crucible was covered but exposed to laboratory atmosphere. These films were determined to be multi-layered graphene by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), Raman and infrared spectroscopy and X-ray diffraction. XPS indicates that the films are primarily sp2 hybridized carbon with small amounts of sp3 C–H and C–O or C–N functionalities. Based on the D band shift (1593 cm−1) and the ratio of D band to G band (1354 cm−1) of 0.93, the Raman spectrum also indicates that the material is sp2 C with some nanocrystalline features. The infrared spectrum exhibits A1U (868 cm−1) and E1U (1599 cm−1) stretching of the intralayer bonds of graphene. This form of chemical vapor deposition may be a scalable to give much larger surface areas. Furthermore, the process does not require metal substrates. Deposition onto silica nanosprings and diatomites is demonstrated.